Google Analytics is a free service that records what visitors do on your website: how many arrive, where they came from, which pages they read and whether they took the actions you care about, such as sending an enquiry. The current version is Google Analytics 4, usually shortened to GA4. The older Universal Analytics stopped collecting data in July 2023.
How GA4 collects data
You add a small Google tag to every page, identified by a measurement ID that starts with G-. Each time something happens, the tag sends an event to Google: page_view, scroll, click on an outbound link, form_start and so on. GA4 is built entirely on events, and its "enhanced measurement" setting records several of these automatically. You choose which events count as key events (Google's current name for conversions), for example generate_lead when a contact form is submitted.
Visitors are grouped into sessions and users using first-party cookies, so where privacy law requires consent, the tag should respect a consent banner. Google's Consent Mode lets the tag adjust its behaviour depending on what the visitor allowed.
A practical setup for a service business
A kitchen fitter wants to know which marketing produces quote requests. The steps:
- Install the Google tag directly or through Google Tag Manager.
- Fire an event when the quote form's thank-you message appears, and mark it as a key event.
- Tag links in emails and social posts with UTM parameters.
- Open the Traffic acquisition report and compare key events by source.
Now "Facebook ad" and "Google organic" can be compared on enquiries, not just visits.
Do you need it?
If you spend money on ads or want to know which pages bring in business, yes. If you only need a visitor count, a lighter privacy-focused counter may be simpler and avoids a consent banner in some regions. Pair GA4 with Google Search Console, which shows search queries that GA4 cannot see on its own.
GA4 mistakes that ruin the data
- Leaving data retention at the default. GA4 keeps detailed event data for 2 months unless you raise it to 14 in the admin settings.
- No key events defined. Without them you only learn about traffic, not results.
- Installing the tag twice. Once in the theme and once through Tag Manager doubles every page view.
- Counting your own visits. Define internal traffic and filter it out.
- Expecting it to match other tools. Ad platforms, GA4 and your server logs count differently; look at trends.
Related terms
- Google Search Console: search data from before the visit.
- Google Tag Manager: a common way to install and extend GA4.
- UTM parameters: labels that tell GA4 where a visit came from.
- Conversion rate: a figure GA4 helps you track.